I have an Avic z2 i bought used from someone - i know i should of checked it out thoroughly but my issues is with playing DVD's... i popped the dvd in no pictures pops up but the sound does. i get the same ole never drive watching etc etc also and prompts me to hit ok... on the screen it shows where i can pause stop skip etc etc but no picture at all... is this normal - do i have to hookup something? anyone knows let me know thanks!!!